evaluation and integration of soil salinity and water data for improved land use of underproductive...

EVALUATIONAND INTEGRATION OF SOIL SALINITYANDWATER DATA FORIMPROVED LAND USE OF UNDERPRODUCTIVE COASTAL AREA IN ORISSAy

MADHUMITA DAS*, R. R. SETHI AND N. SAHOO

Water Technology Centre for Eastern Region, Chandrasekharpur, Bhubaneswar 751 023, Orissa, India

ABSTRACT

Coastal agriculture in Orissa is predominantly rainfed and hence vulnerable owing to uncertain distribution of

rainfall over time. Lack of irrigation support and salt stress affect crop growth and reduce yield as well. Good

quality aquifer and low-saline soil are available but vary spatially. Promoting potential use of spatially varied

resources, precise assessment of soil and water quality at micro-level is therefore imperative. In this study the soil

salt stress, availability and quality of underground aquifers at different sites were evaluated in the neighbourhood

area of Chilika, the largest brackish water lagoon of Asia. Integrating soil salinity, soil moisture content, aquifer

availability and quality, various farming strategies specific to different sites were developed. These could trigger

1.59 to 2 times more production from its present level in that area. Where there is a diverse occurrence of resources,

a precise estimation of those resources’ potentials thus provides keys to develop cost-effective options for

improving production in an underproductive area. Copyright # 2010 John Wiley & Sons, Ltd.

key words: spatially varied resources; farming strategies; underproductive area

Received 22 February 2008; Revised 9 February 2009; Accepted 3 March 2009

RESUME

L’agriculture du littoral de l’Orissa est essentiellement pluviale et donc vulnerable en raison de la distribution

temporelles incertaine des precipitations. Lemanque d’irrigation et le stress du au sel affectent la croissance des cultures

et ainsi reduisent le rendement. Un aquifere de bonne qualite et des sols peu salins sont disponibles, mais varient dans

l’espace. Il est donc imperatif de promouvoir l’utilisation des ressources potentielles variables dans l’espace,

l’evaluation precise des sols et de la qualite de l’eau a micro-echelle. Dans cette etude, la salinite du sol, la disponibilite

et la qualite des aquiferes souterrains dans les differents sites ont ete evalues dans la zone de Chilika, la plus grande

lagune d’eau saumatre de l’Asie. En integrant la salinite du sol, la teneur en humidite des sols, la disponibilite et la

qualite de l’aquifere, des strategies agricoles specifiques aux differents sites ont ete developpees. Celles-ci pourraient

declencher dans cette zone 1,59 a 2 fois plus de production par rapport au niveau actuel. Pour diverses occurrences de

ressources, l’estimation precise des ressources potentielles fournit ainsi des cles pour developper des options efficaces

pour ameliorer la production des zones les moins productives. Copyright # 2009 John Wiley & Sons, Ltd.

mots cles: ressources variees dans l’espace; strategies agricoles; region peu productives

INTRODUCTION

Coastal agriculture occupies a major portion of available farmlands, provides livelihood support for the rural

population, but often suffers from salt stress; the freshwater shortage leads to poor production in different areas

IRRIGATION AND DRAINAGE

Irrig. and Drain. 59: 621–627 (2010)

Published online 28 June 2010 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ird.519

*Correspondence to: Madhumita Das, E-mail: [email protected] des differentes methodes d’irrigation par une approche d’evaluation parametrique dans la plaine

Copyright # 2010 John Wiley & Sons, Ltd.

(FAO, 1998). A large tract along the east coast of India is cultivated mainly for rice during the monsoon and usually

remains fallow afterwards. Salinity increases with progress of the dry period (Bandyopadhyay, 1972; ORSAC,

1986) and becomes aggravated under fallow. The excess presence of salt disperses soil structure, reduces

permeability, accelerates the soil degradation process and consequently makes the situation not conducive to plant

growth (Agassi et al., 1981; Abu-Sharar et al., 1987). Aquifers of low to high salt content are available but vary

inconsistently in space especially under the hard rock region (Patnaik, 1994). The availability and salinity of

underground water at shallow depth determine soil salinity, which thus varies irregularly across space as well. The

freshwater aquifer and low-saline soil could be used for cultivation during the post-monsoon period if exact

information is known on the degree of salt stress and water availability at different periods. For spatially variable

resources, micro-level assessment of soil and water quality is therefore a prerequisite to understanding the land’s

potential and enable appropriate uses in farming.

The area adjacent to the periphery of Chilika, the largest brackish water lagoon in Asia, is cultivated only for rice

during the monsoon season (June–October). The rice yield is also low (<1 t ha�1 as against national average

2 t ha�1). The area is underlain by consolidated hard rock and characterized by variable soil and groundwater

conditions (Das, 1994). Agriculture is at subsistence level. The present study was undertaken with two objectives:

(1) assess soil and water with respect to its salt stress distribution in space and fluctuation with the seasons, and (2)

develop farming strategies by integrating soil, water and hydrological information for improving crop production in

the underproductive coastal area.

MATERIALS AND METHODS

Selection of study area

Two locations strikingly different in all respects but representing the neighbourhood area of Chilika lagoon were

chosen for the study. The first is located between 8582802000 N and 20810 E, covering an 85 ha area near to the

channel (Magarmukh channel) carrying saline water from the sea to the lagoon, at Bhusandpur, in coastal Orissa,

India. The second was at Kalupadaghat, covering 83.5 ha in area, located at 1985204200 N and 8582405300 E and

adjacent to the lagoon. Soil and aquifer characteristics were studied in each location with different land morphology

and distance of separation from the lagoon by carrying out exploratory drilling. The quality of water was assessed

by determining pH, EC and salinity-related properties. Soil profiles (up to 1.5m depth in 0.15m increments) were

collected from each drilling site and analysed for pH, EC2, ECe, soil moisture content at saturation and field

capacity by following standard procedures. The Bhusandpur area was relatively more stressed by salt than the

Kalupadaghat area. Soil samples were therefore collected by covering the entire area from 0–0.2 and 0.2–0.4m

depths to determine maximum salt stress in the root zone during the first week of June (i.e. at the pre-monsoon

period). Relationships between soil salinity and moisture were established to determine soil salinity in situ for that

area.

To monitor groundwater salinity, observation wells (2.5m depth with 0.076m diameter) were installed at<100,

100–200 and >200m distances from the lagoon in each study area. Water salinity and water-table depth were

measured once a month for two years. Soil salinity adjacent to the observation wells up to 1.5m depth with 0.15m

intervals was monitored as well.

Using SURFER 8.0 the groundwater availability and salinity contours were prepared. Then by considering soil

salinity, aquifer availability and salinity, farming strategies were developed specific to different sites in the study

areas.

In Bhusandpur, 30% of the area was allocated for growing pulses (gram, blackgram, pea, moong), 40% for

vegetables (cucumber, sugar beet, chilli, tomato, etc.), 20% for cereals (maize, barley) and 10% for oilseeds

(safflower), having due consideration to local preferences for growing a variety of crops. Considering 0.7, 5.0, 1.5

and 0.7 t ha�1 respectively as an average yield of pulses, vegetables, cereals and oilseeds, the production scenario

was made and depicted in Table I. In Kalupadaghat, salt stress was relatively low and hence considered suitable for

growing high-value crops like vegetables by developing a rain water harvesting structure. Considering mean yield

as 5 t ha�1 for vegetables, the targeted production was focused for the area (Table I).

Copyright # 2010 John Wiley & Sons, Ltd. Irrig. and Drain. 59: 621–627 (2010)

DOI: 10.1002/ird

622 M. DAS ET AL.

RESULTS AND DISCUSSION

Developing relationships between salinityand soil moisture

In Bhusandpur salinity of the saturated soil extract (ECe) did not relate with soil moisture content either at field

capacity (ufc) or at saturation (us). But electrical conductivity physically depends on soil moisture and texture.

Wetter soil is electrically more conductive than drier soil and coarser soil tends to be less so than finer soil (Inman

et al., 2002). However EC2 was significantly related to ufc and us and also to ECe for both soil depths (Table II).

Salinity and soil moisture are the integrated measures of many soil properties, e.g. clay content, bulk density,

texture, and hence can be used as diagnostic tools for precision farming (Corwin et al., 2006; Carroll and Oliver,

2005). The relations developed between soil salinity and soil moisture could thus be used either individually or in

combined forms to estimate salt stress in situ.

Appraisal of soil properties

In Bhusandpur, soil pH ranged from 5.9 to 7.8 with an increasing trend downward in the profile. Specifically, the

soil at <100m was 5–10% more acidic (pH) in reaction than the soils at 100–200 and >200m distances from the

lagoon and showed a decreasing trend from January to May. Salt build-up in soil was not significant during

January–March, increased after that and showed a decreasing trend from the surface to subsurface layers in the

profile. But the increase or decrease of salinity was not consistent either with soil depth or advance of the dry period.

This was also corroborated by the spatial distribution of salinity as illustrated in Figure 2. It shows that salinity was

at a maximum at the north-east corner of the area, located near the brackish water source, and may thus reflect the

influence of the lagoon. Soils with different salt content were also clustered at the southern part of the area. Spatial

variation in soil and water salinity along with its fluctuation with the seasons was also observed and reported at an

8 ha farm area in the Sundarban delta (Das and Maji, 2001).

Table I. Targeted production level of the study area

Location Area focusedon (ha)

Presentpractice

Present production(t)

Excess productiondue to intervention (t)

Overall productivityscenario (t)

Bhusandpur 83.5 Monsoon paddy 141.95 84.42 226.37Kalupadaghat 85.0 Monsoon paddy 127.50 127.50 255.00

Table II. Relations between salinity and soil moisture for Bhusandpur area

Constituents Forms of expressions (ECe dS m�1) R2 F- ratio (significant at 0.01 level)

At 0–0.2m soil depthEC2 (dS m�1) ECe¼ 0.13þ 2.34 (EC2) 0.84 235.56

ECe¼ 0.34(EC2)0.95 0.78 235.56

EC2 (dS m�1), us (cm3 cm�3) ECe¼ 0.58þ 2.36(EC2) – 0.68(us) 0.85 117.57

EC2 (dS m�1), ufc (cm3 cm�3) ECe¼ 0.45þ 2.39(EC2) – 0.93(ufc) 0.85 119.59

At 0.2 – 0.4m soil depthEC2 (dS m�1) ECe¼ 0.28þ 1.68(EC2) 0.71 105.64

ECe¼ 0.37(EC2)0.92 0.71 105.64



Combined forms for both soil depthsEC2 (dS m�1) ECe¼ 0.21þ 1.99 (EC2) 0.81 338.33

ECe¼ 2.14(EC2)0.83 0.79 338.33




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EVALUATION OF SALINITY DATA FOR IMPROVED LAND USE IN ORISSA 623

The soil was high to moderately acidic in reaction (pH 4.2–6.4) in Kalupadaghat. Salt content (ECe) was enriched

by 1.7–4.0, 3.1–4.3, and 1–2.5 times respectively at <100, 100–200 and >200m distances from Chilika, from the

post- to pre-monsoon period.

Appraisal of the underground aquifer

The groundwater table depth varied from 1.5 to 2m below the surface during November –January and went

beyond 2m afterwards in Bhusandpur. The groundwater salinity (EC) at a distance <100, 100–200 and >200m

from the lagoon varied from 4.7 to 7.6, 3.5 to 4.9 and 2 to 3.5 dSm�1 respectively, while pH fluctuated from 7.3 to

7.7. The EC varied from 0.6 to 16.7 dSm�1 at 1.6–2.2m depth without showing any trend either with distance from

Chilika or progress of the dry period. Moreover a sharp difference in groundwater salinity at a same distance from

the lake was also evident at different sites.

The groundwater table fluctuated from 0.6 to 1.5m from January to May in Kalupadaghat, with lower depth (i.e.

<1.0m from surface) at<50m, and higher (>1.0m) at>100m from the lake. Overall, the pH changed from 7.8 to 8.9

and EC from 5 to 6.7 dSm�1. But a low-saline zone (EC¼ 1–2 dSm�1) prevailed at a depth 0.5–1.3m from the

surface, in the area 50–100m from the lagoon. Besides, groundwater available at<1.0m depth had pH¼ 7.8–8.4 and

EC¼ 2.5–4.0dSm�1 in the area close to the lagoon (>50m) and thus revealed the contrasting nature of resources in

the study area.

Substrata and aquifer characteristics

In Bhusandpur, the presence of alluvium and gravel layers was distinct in the substrata (Figure 1A). Typically

substrata of the area reflected that the aquifer materials were non-uniform as uniformity coefficient (Cu) <5 in more

Figure 1. Substrata conditions of Bhusandpur and Kalupadaghat area


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624 M. DAS ET AL.

than 80%of the samples. The upper layer was porous though thewater yield was too low tomeet irrigation requirement

of the area. Availability of the first aquifer was observed beyond 6m down from the surface. Amount of rechargewater

per hour fluctuated from 5.44 to 8m3, and ffi10m3 during non-monsoon and monsoon periods, while transmissivity

varied from 214 to 312m2 day�1. A saline zone (EC 7.7–10.8 dSm�1) with 1.82– 4.23m aquifer thickness was

apparent at various depths in the south and south-west corners of the area (Figure 3). But a relatively less saline zone

(EC 0.5–1.2 dSm�1) at 4.23–5.34m depth down from the surface in thewest and north-west, and amarginal saline (EC

2–3dSm�1) zone at>5.34m depth were spotted in the east and north-eastern parts of the area. Occurrence ofa saline

aquifer did not reveal the influence of the brackish water lagoon present at the south-east corner of the study area.

The non-uniformity in the availability of the underground aquifer, water table depth, yield characteristics and

quality of water in the coastal area was also observed by Das (2000). Moreover, the presence of a freshwater zone

through rainwater infiltration in the sandy layer over saline groundwater along the coastal tract was also reported by

Gupta et al. (2000).

In Kalupadaghat, the substrata were dominated by a hard clay/laterite clay layer at 3–3.5 m depth from the

surface in general (Figure 1B). A permanent aquifer 4.5–6m below the surface was observed at a distance

>10m from the lagoon. But a subsurface water table at the same depth with different salt stresses and vice versa,

Figure 2. Soil salinity distribution in Bhusandpur area

Figure 3. Aquifer characteristics in Bhusandpur area


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was evident in the area (Figure 4). The presence of laterite clay was common in the area near to the brackish

water lagoon. The laterite and hard clay layers (Figures 1A and B) indicated the presence of a consolidated hard

rock zone in the area. Crystalline hard rock underlain by mostly Quaternary alluvial formations and the

presence of laterite had already been recognized in the coastal tract of Orissa (CGWB, 2004).

Farming strategies

In Bhusandpur, the extent of salt stress (ECe 0.1–2.0 dSm�1), fine soil texture and aquifer salinity in alliance

indicated that a rain water harvesting structure, e.g. a pond or dug well (WHS, up to 2m deep) with convenient size as

per farm holdings (usually <2ha) may be developed in the north and western parts of the study area. The developed

freshwater reservoir could be utilized for pisciculture and also as an irrigation source. Low-salt-tolerant crops like

pulses, e.g. green gram, horse gram, black gram,. could be grown with one or two supplemental irrigations in the area.

An areawith similar substrata but in the presence of a saline aquifer at 2–4.23m depth from the surfacewith soil salinity

(ECe) ranging from 1.4 to 3.3 dSm�1 was found suitable for growing salt-tolerant crops like barley, safflower, tomato,

sugar beet and the like at the southern border of the area (Figure 1). Appearance of low-saline (ECe 0.7–1.4 and 2.0–

2.7 dSm�1) stretches, which are unevenly distributed spatially, could also be used for cultivating low-salt- tolerant

crops preferably during the winter and summer seasons. This apart, the occurrence of a marginally saline aquifer at

various depths accompanied by soil of moderate to high salt stress (ECe 1.4–5.2 dSm�1), which becomes concentrated

from December to June, was not found favourable for developingWHS along the eastern border of the area (Figures 1

and 2). The area could be cultivated for low-water-requirement and high-salt-tolerant crops during the winter. In the

entire study area, the non-uniform distribution of low-saline soil patches (ECe 0.1–1.4 dSm�1) from the north-west to

south-east directions could be used for cultivating low-salt-tolerant crops. Besides, as per availability of low saline/

fresh water in WHS, any food crop could be taken up after monsoon rice at these sites.

In Kalupadaghat, the depth of the underground aquifer increased diagonally from the north-west (i.e. the location

adjacent to the lagoon) to the south-east corner of the entire area (Figure 4). But the presence of the subsurface aquifer

at 2–2.5m depth from the surface coupled with a 4–5m3 h�1 recuperation rate and low water salinity (EC<4 dSm�1)

Figure 4. Depth and salinity of underground aquifer in Kalupadaghat


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626 M. DAS ET AL.

was found suitable to create a dug well structure up to 2.5m depth (length and width as per convenience) in the north-

west of the area. Incidence of saline aquifers (EC 4–14 dSm�1) at 4–5m depth was evident in the extreme east and

south-west parts of the area (Figure 4), and not found feasible for developingWHS for supplying irrigation. The soil at

Kalupadaghat was relatively less saline than that observed at Bhusandpur and thus was suitable to grow any seasonal

crop with existing WHS in the entire study area. These location-friendly farming strategies would enable extension of

the crop area by utilizing site-specific land potential during the post- and pre-monsoon periods.

Productivity scenario

At present 85 and 83.5 km2 area are solely under monsoon-rice cultivation in Bhusandpur and Kalupadaghat

respectively. A small portion of it is also being used for growing winter crops, chiefly pulses. The productivity

scenario of the underproductive study area (Table I) reflects that by proper utilization of land potential and/or

tapping a good quality aquifer by creating a pond or dug well, production level could reasonably be improved by 1.6

to 2 times from its present level. Thus for a diversified presence of natural resources, micro-level evaluation of land

potential is essential, particularly in underproductive regions. This would help to modify the existing state of the art

by promoting precise use of soil, water and land resources towards improvements.

CONCLUSIONS

Soil salinity, moisture content, underground aquifer availability, groundwater quality and their spatial distribution

revealed the site-specific land potential of an underproductive coastal area in India. Integrating these, a variety of

options suiting local contexts were developed for improving production. Thus to achieve the potential productivity

of a heterogeneous system, prioritizing constraints and their thorough understanding enable us to offer ways and

means to exploit land capacity for promoting cropping in underproductive regions.

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